Rufous Fantail (Rhipidura rufifrons)

Compiled by: Shelly Kremer, USFWS, Honolulu, Hawaii, Peter Luscomb, Pacific Bird Conservation, Honolulu, Hawaii, and Paul Radley, CNMI Division of Fish and Wildlife, Saipan Order: Passeriformes Family: Corvidae Subfamily: Dicrurinae Tribe: Rhipidurini Local or Chamorro Name: Naabak SPECIES OVERVIEW Description: A small, sexually monomorphic, monarchid flycatcher (Jenkins 1983), with cinnamon forehead and crown that contrast with black orbital rings and white malar stripes. The anterior chin is white becoming black towards the posterior along the throat and upper breast. Lower breast is spotted brown and white, underwings grayish to buff, abdomen, sides, flanks, and tibia all darker brown than the head. The lower back and base of tail bright rufous, rectrices tipped with white. The bill is black and the feet and irides are dark brown. Immature birds resemble adults, but head, neck, and scapulars are rufous edged, and the black feathering of the chin and throat are edged with white (Pratt et al. 1987; Jenkins 1983). Molt begins in July and continues through the fall (Baker 1951).

Distribution: Two subspecies are common on Saipan, Tinian, Aguiguan (R. r. saipanensis) and Rota (R. r. mariae), while the Guam subspecies (R. r. uraniae) is believed to be extinct. Another subspecies (R. r. versicolor) is found on the island of Yap, with an additional 14 subspecies occurring through Australasia (Pratt et al. 1987, Clements et al. 2012). The population of Rufous Fantails on Saipan, Tinian, Aguiguan, and Rota was reported in 1982 to be approximately 2,194, 1,634, 455, and 1,049, respectively (Engbring et al. 1986). Point-transect distance surveys conducted at the same stations on Saipan in 2007, and Tinian and Aguiguan in 2008 yielded abundances of 52,318 (95% CI 39,703 – 70,057), 68,884 (95% CI 61,297 – 77,069), and 10,939 (95% CI 8,248 – 14,671), respectively (Amidon et al. in review , Camp et al. 2009, Camp et al. 2012). Subsequent analysis of data from Rota, including the Enbring island-wide Variable Circular Plot (VCP) surveys (1982–2004) and Rota Bridled White-eye VCP surveys (2002-2005), show a significant decline in Rufous Fantails populations (Ha 2006). However, Breeding Bird Surveys (BBS) on the island from 2000 to 2005 show no change in overall abundance for Rufous Fantail populations. Analysis of the Saipan BBS data, however, shows a significant increase followed by a significant decline in the species population from 1991 – 2010 (Kremer et al. in review). Habitat: Rufous Fantails occur in native limestone forest and disturbed habitats, including beach strand and suburban areas (Craig 1996). Baker (1951) noted a preference of fantails for forest and scrub communities, Marshall (1949) documented their abundance in woodland understories, and Strophlet (1946) recorded them in riparian communities on Guam. The species, however, does appear to be largely absent from swordgrass savannah (Craig 1996). Sachtleben (2005) reported nesting densities to be almost evenly distributed among forest types with densities ranging from 0-16/km2 in native/mixed forest, and 0-25/km2 in non-native forest, depending upon the month of survey. Food and Feeding Habits: The species commonly forages both in the canopy and mid/lower strata (Craig and Beal 2001). Fantails are insectivorous and hawk for insects from perches, primarily catching prey on the wing (Jenkins 1983). Flights are usually horizontal and several insects are usually taken before the bird alights (Marshall 1949). Jenkins (1983) also observed fantails gleaning insects from branches among the foliage, and Craig and Beal (2001) documented them foraging equally both from leaves and in an aerial manner, specializing in sallying and hovering. Rufous Fantails often follow Golden White-eyes (Cleptornis marchei) and Bridled White-eyes (Zosterops conspicillatas) to capture insects flushed by the foraging activities of these two species (Jenkins 1983; Craig 1996). Behavior: Fantails are extremely active birds, constantly flitting about in the understory searching for food (Jenkins 1983). Although agile in the understory, flight appears labored when crossing forest openings or roadways, birds undulating slowly at low altitudes of only 1-2 m (Jenkins 1983). They are frequently found in pairs or in small groups of three to five individuals, which are most likely family groups (Craig 1996). Fantails tend to continually spread their long, fan-like tails (Jenkins 1983), almost never completely fold their wings, and frequently exhibit hostility towards one another (Marshall 1949). Color banding showed that groups remained at single locations, and at such locations males engaged in singing duels with neighbors and responded aggressively to taped playbacks of fantail songs. Individuals appear to defend all- purpose territories and observations of interspecific aggression include supplanting perched Bridled White-eyes, chasing foraging Golden White-eyes near fantail nests, and chasing foraging Micronesian Honeyeaters (Myzomela rubrata; Craig 1996, S. Kremer, unpubl. data). The species appears to have no pattern of diurnal activity levels, including singing (Craig and Beal 2001). Breeding: Craig (1996) documented active fantail nests on Saipan in January, February, March, April, October, and November, while Pyle et al. (2012) reported birds on the island in breeding condition every month of the year. Jenkins (1983) reported breeding from January to April and in June and November on Guam. Nesting: Fantail nests are compact, usually built around a branch or fork of a tree, and are composed of fine grasses, Casuarina needles, hair-like matter, and spider webs, all of which is held together by a mucous-like secretion (Jenkins 1983). Nests are usually supported by two to three branches but have been found supported by only one or up to four (Sachtleben 2005, unpubl. data). Nests have been document built from 0–2.3 m from the trunk of the tree (mean = 0.6 m; Sachtleben 2005, unpubl. data). Sachtleben (2005, unpubl. data) reported the following nest measurements on Saipan: mean inner nest cup diameter of 42 mm (range = 37–46 mm; n = 49); mean outer cup diameter of 51 mm (range = 44–55 mm; n = 49); mean depth of cup of 22 mm (range = 17–30 mm; n = 52); mean nest height of 46 mm (range = 31–60 mm; n = 52); mean length of nest "tail" of 64 mm (range = 0–147 mm; n = 51). Jenkins (1983) reported that nests on Guam were about 37 mm in outer diameter. enkins (1983) documented nests in Hibiscus tiliaceus and Leucaena leucocephala on Guam. Sachtleben (2005, unpubl. data) reported the following nesting trees on Saipan: Aidia cochinchinensis (n = 6), Albizia lebbeck (n = 2), Cynometra ramiflora (n = 9), Eugenia spp. (n = 4), Guamia mariannae (n = 22), Leucaena leucocephala (n = 36), Maytenus thompsonii (n = 1), Melanolepis multiglandulosa (n = 1), Ochrosia mariannensis (n = 1), Pithecellobium dulce (n = 2), Psychotria spp. (n = 1). On Rota, nests were also found in Hernandia labyrinthica (n = 1), Merrilliodendron megacarpum (n = 2), and Piper guahamense (n = 2) (Amidon, unpubl. data). On Saipan, mean nest height was 2.1 m (range = 0.5–6.5 m; n = 101) while the mean height nest trees was 4.4 m (range = 0.8–12.6 m; n = 100; T. Sachtleben 2005, unpubl. data). The most common nest predators on Saipan are believed to be Micronesian Starlings and Collared Kingfishers and forest type did not affect nesting success/survival (Sachtleben 2005). Sachtleban (pers. comm.) noticed that there was often quite a long delay between nest building and egg lying. Eggs, incubation, hatching, and growth and development: Fantails typically lay two eggs that are dull white and ringed with brownish spots diffused around the center or nearer their large end (Jenkins 1983). Both adults typically incubate and brood the young (Jenkins 1983). Incubation is 15–17 days and the nestling stage 12–17 days (T. Sachtleben 2005, unpubl data). Jenkins (1983) reported a brood of fantails fledging on Guam in 14-15 days. Both adults feed young but one (sex undetermined) appears to feed more often (Jenkins 1983). Chick Development: The following is adapted from T. Sachtleben 2005, unpubl. data. Day 0; hatch at ~1.5 cm long, dark pink/purple skin, either naked or covered with light fuzzy down. Day 1; 1.5–2 cm long, dark pink/purple skin, usually with light down on the head and often on the body. Day 3; 2.5–3 cm long, skin color pale to dark pink, wing pins 1–3 mm long with back pins beginning to erupt, still no head pins, and generally still covered in light down on the head and back. Day 6; ~4 cm long, skin color light to dark pink/purple, wing pins may be 4–8 mm long, back pins 2–3 mm, head pins visible (i.e., just poked through), head is still covered in down. Feathers may barely be erupting from the wing and back pins at this stage of development. Day 9; 4–5 cm long, dark grey feathers from 4–10 mm long have erupted from pin tracts on wings, rufous feathers 4–5 mm long from the pin tracts on the back, head pins have erupted, as have tail pins (~2 mm). Eyes cracked open but don't seem to open any earlier. Day 12;~5 cm long, eyes open, and fully feathered although the feathers still look downy, but head pin tracts are still visible.